1. Field of the Invention
This invention concerns a drive control device for a conveyor of the type having a plurality of linked support-carriages which run along a rail.
2. Description of Related Art
Conveyors of the type utilizing a plurality of support-carriages running along an overhead rail are employed in assembly line operations, for example, to transport parts automatically to locations where they are needed. In such a conveyor device, drive motors are used to drive wheels on the support carriages which cause them to move along the top of the rail. Some conveyors of this type have the various support carriages linked together. When all of the drive wheels on the support-carriages have the same diameter, the overall speed of the linked support carriages can be controlled by keeping the number of revolutions per minute (rpms) of the drive wheels identical.
This type of speed control, however, is disadvantageous in that torque imbalances tend to arise among the various support-carriages resulting from difference in weights of the individual loads, and so forth, which affects the loads on the respective drive motors. Particularly in cases of very heavy loads, the drive motors are subject to overheating and breakdown.